Pilot reported burning plastic odor and visible fumes in the cockpit during approach. Pilot requested special handling and was given landing clearance where a safe landing was executed.

Narrative

While flying from ZZZ1 -> ZZZ in a Piper Warrior. The plane flies regularly; once every week or two. After getting clearance to land at ZZZ and shortly after entering the Delta airspace I smelled a burning plastic smell. Initially I thought maybe it was just my imagination; it's an old plane and sometimes it makes weird smells.After about 20 seconds the smell got stronger and I saw visible fumes starting to come from underneath the panel; I realized that the #2 Radio had turned off. I called the Tower and immediately [to advise]. I stated that there appears to be a potential beginning of an electrical failure and I smell and see smoke.I saw the #2 Radio was at this point inactive. The breaker wasn't popped; so rather than try to fiddle with it I asked the Tower to roll emergency services and I was turning off the electrical system and would lose my radio. They repeated 'Cleared to land Runway 4; emergency services are on their way' (something like this) After landing with the emergency crews there; and safely taxiing off the runway; I popped the breaker for #2 Radio and turned the master back on. No smoke or failure; I taxied back to the FBO with Radio #1 and electrical systems on. Emergency services scanned the panel with an infrared sensor to make sure there wasn't a fire behind the panel we didn't see/smell. Everything was normal. The initial conclusion (I'll have the shop get it in this week before the plane goes back out) - Radio #2 malfunctioned creating smoke in the cabin; IT DIDN'T POP THE BREAKER. With the breaker out manually; it seemed to have resolved the problem and the issue appears to have been isolated to just the radio itself and not the harness or wiring.