Moderates needing restraint, being without power (7)

'moderates' is the definition.
(dampen can mean to moderate or decrease)

'restraint being without power' is the wordplay.
I cannot really see how this works, but
'restraint' could be 'dam' (I've seen this before) and 'dam' is found in the answer.
'being' could be 'ens' (philosophical term for being or existence) and 'ens' is found within the answer.
'power' could be 'p' (symbol in physics) and 'p' is located in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).

'needing' is the link.