For a chap prowling round, the entrance (8)
I believe the answer is:
approach
'the entrance' is the definition.
(thesaurus)
'for a chap prowling round' is the wordplay.
'for' becomes 'pro' (as in being 'pro' something).
'prowling' is an anagram indicator (prowl means to move around).
'round' means one lot of letters goes inside another.
'chap' with letters rearranged gives 'apch'.
'pro'+'a'='proa'
'proa' going inside 'apch' is 'APPROACH'.
(Other definitions for approach that I've seen before include "attitude" , "Come towards" , "Come close" , "initial proposal" , "technique" .)