Captured tank, perhaps, out East (5)
I believe the answer is:
taken
'captured' is the definition.
(I've seen this before)
'tank perhaps out east' is the wordplay.
'perhaps' is an anagram indicator.
'out' means one lot of letters goes inside another.
'east' becomes 'e' (synonyms).
'tank' anagrammed gives 'takn'.
'takn' enclosing 'e' is 'TAKEN'.
(Other definitions for taken that I've seen before include "Captured" , "This is spoken for" , "Removed, accepted" , "Seized" , "Kidnapped" .)