Army officer -- pass one beginning to limp (7)
I believe the answer is:
colonel
'army officer' is the definition.
(I've seen this before)
'pass one beginning to limp' is the wordplay.
'pass' becomes 'col' (col is a term for a mountain pass).
'beginning to' suggests taking the first letters.
The initial letter of 'limp' is 'l'.
'col'+'one'+'l'='COLONEL'
(Other definitions for colonel that I've seen before include "Commander" , "Rank (below brigadier)" , "Army rank" , "Army officer ranking below a brigadier" , "Senior army officer" .)