Probably with an ulterior motive, he gives a girl a bit of supper (5)
I believe the answer is:
viper
'probably with an ulterior motive he' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'a girl a bit of supper' is the wordplay.
I cannot really see how this works, but
'a' could be 'per' (eg 'one a day' means 'one per day') and 'per' is found within the answer.
'girl' could be 'vi' (short for Violet) and 'vi' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'gives' is the link.
Can you help me to learn more?
(Other definitions for viper that I've seen before include "Malicious type" , "poisonous type" , "Venomous snake, person" , "A small poisonous snake" , "crawler" .)