Increase sunlight, did you say? (5)
I believe the answer is:
raise
'increase' is the definition.
(I know that raise is a type of increase)
'sunlight did you say?' is the wordplay.
'sunlight' becomes 'rays'.
'did you say?' indicates a 'sounds like' (homophone) clue.
'rays' is a homophone of 'RAISE'.
(Other definitions for raise that I've seen before include "Make higher" , "rally" , "Increased earnings in America" , "Bring up - an increase in pay" , "Lift, elevate" .)