Image captures prince left looking like a plonker (7)
I believe the answer is:
phallic
'looking like a plonker' is the definition.
I can't tell whether this definition defines the answer.
'image captures prince left' is the wordplay.
I cannot quite see how this works, but
'prince' could be 'hal' (I've seen this before) and 'hal' is found in the answer.
'left' could be 'l' (common abbreviation) and 'l' is found in the answer.
'image' could be 'pic' (short for picture) and 'pic' is found in the remaining letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for phallic that I've seen is " Like a penis".)