MP needs support in UN: plenty (7)
I believe the answer is:
umpteen
'mp needs support in un plenty' is the definition.
I can't judge whether this defines the answer.
'mp needs support in un' is the wordplay.
'needs' is a charade indicator (letters next to each other).
'support' becomes 'tee' (tee is a kind of support).
'in' means one lot of letters goes inside another.
'mp'+'tee'='mptee'
'mptee' put into 'un' is 'UMPTEEN'.
Can you help me to learn more?
(Other definitions for umpteen that I've seen before include "Countless" , "Pet menu for a great many" , "Lots of things on pet menu" , "Indefinitely many" , "An uncountable number" .)