Holiday location mounted across uniform pocket (7)
I believe the answer is:
trouser
'pocket' is the definition.
(both can mean to steal or take)
'holiday location mounted across uniform' is the wordplay.
'holiday location' becomes 'resort' (I've seen this before).
'mounted' is a reversal indicator (in a down clue, letters mounted up).
'across' is an insertion indicator.
'uniform' becomes 'U' (phonetic alphabet: alpha, bravo, charlie etc.).
'resort' backwards is 'troser'.
'troser' enclosing 'u' is 'TROUSER'.
(Other definitions for trouser that I've seen before include "Appropriate" , "Pocket (slang)" , "Pocket (something)" , "Our rest (anag)" , "For oneself" .)