Worked hard to muster new voters (6)
I believe the answer is:
strove
'worked hard' is the definition.
(I've seen this in another clue)
'new voters' is the wordplay.
'new' indicates anagramming the letters.
'voters' is an anagram of 'STROVE'.
'to muster' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for strove that I've seen before include "Made great efforts" , "Tried hard for voters" , "Voters (anag) - made every effort" , "Struggled" , "Endeavoured" .)