Random man's blown top with difficult to comprehend street map (9)
I believe the answer is:
haphazard
'random' is the definition.
(similar in meaning)
'man's blown top with difficult to comprehend street map' is the wordplay.
'man' becomes 'chap' (term for a man).
'blown top' means to remove the first letter (the top letter is blown away).
'with difficult' becomes 'hard' (synonyms. I am not sure about the 'with' bit.).
'to comprehend' indicates putting letters inside (comprehend can mean to contain or include).
'street map' becomes 'A-Z' (an 'A to Z' is a street map).
'chap' with its first letter removed is 'hap'.
'hard' placed around 'az' is 'hazard'.
'hap'+'hazard'='HAPHAZARD'
(Other definitions for haphazard that I've seen before include "Slapdash, slipshod" , "Erratic" , "Lacking any obvious organisation" , "Careless or random" , "Disorganised, random" .)