Vulgar fellow has energy (5)
I believe the answer is:
cheap
'vulgar' is the definition.
(synonyms)
'fellow has energy' is the wordplay.
I cannot really see how this works, but
'fellow' could be 'he' ('he' refers to a man) and 'he' is found within the answer.
The remaining letters 'cap' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for cheap that I've seen before include "Second-rate" , "Not expensive - trashy" , "A snip" , "Tawdry - inexpensive" , "Low in price or tastelessly showy" .)