Ill-tempered taxi driver parked around rear end (6)
I believe the answer is:
crabby
'ill-tempered' is the definition.
(synonyms)
'taxi driver parked around rear end' is the wordplay.
'taxi driver' becomes 'cabby' (I've seen this before).
'parked around' means one lot of letters goes inside another.
'end' says to take the final letters.
The last letter of 'rear' is 'r'.
'cabby' enclosing 'r' is 'CRABBY'.
(Other definitions for crabby that I've seen before include "Bad-tempered, irritable" , "Ill-tempered" , "Bad-tempered, morose" , "In bad temper" , "petulant" .)