Encountered yours truly on top of tram (3)
I believe the answer is:
met
'encountered' is the definition.
('meet' can be a synonym of 'encounter')
'yours truly on top of tram' is the wordplay.
'yours truly' becomes 'me' (the person who set this crossword).
'on top of' suggests taking the first letters.
The initial letter of 'tram' is 't'.
'me'+'t'='MET'
(Other definitions for met that I've seen before include "gathered together" , "Opera company" , "satisfied" , "Encountered by chance or arrangement" , "Encountered or touched" .)