Suspect male is breaking into safe (7)
I believe the answer is:
surmise
'suspect' is the definition.
(I know that suspect can be written as surmise)
'male is breaking into safe' is the wordplay.
'male' becomes 'm' (common abbreviation).
'breaking into' indicates putting letters inside.
'safe' becomes 'sure' (both can mean secure).
'm'+'is'='mis'
'mis' placed into 'sure' is 'SURMISE'.
(Other definitions for surmise that I've seen before include "Conjecture; Cortez's men's was wild (Keats)" , "Conjecture from misuser" , "Presume -- rue miss (anag)" , "Rise sum to guess" , "Suppose without evidence" .)