Is no longer in Pugwash (3)
I believe the answer is:
was
'is no longer' is the definition.
(I've seen this before)
'in pugwash' is the wordplay.
'in' says the answer is hidden in the clue.
'WAS' can be found hidden inside 'pugwash'.
(Other definitions for was that I've seen before include "(I/he/she/it) existed" , "Existed in the past" , "Is no longer" , "Used to be" , "(He/she) existed" .)