A little extra is equivalent to a salary increase (5)
I believe the answer is:
raise
'to a salary increase' is the definition.
(I've seen this in another clue)
'a little extra is equivalent' is the wordplay.
'a little' indicates the answer is hidden within the clue (a little bit of the clue).
'RAISE' is hidden in the letters of 'extra is equivalent'.
(Other definitions for raise that I've seen before include "cairn" , "Cultivate by growing" , "Increased earnings in America" , "Hoist" , "What a poker player might do" .)