Staines Massive leader new to line up (5)
I believe the answer is:
align
'line up' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for align that I've seen before include "Straighten -bring into conformity" , "Make (things) fit together" , "Dress; make straight" , "Straighten in relation to others" , "Put into a straight row" .)