Increase in clubs needing member's support (5)
I believe the answer is:
climb
'increase' is the definition.
(I know that climb is a kind of increase)
'clubs needing member's support' is the wordplay.
'clubs' becomes 'c' (abbreviation in card games).
'needing' is a charade indicator (letters next to each other).
'member's support' becomes 'limb' (I am not sure about this - if you are sure you should believe this answer much more).
'c'+'limb'='CLIMB'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for climb that I've seen before include "increase" , "Move upwards, ascend" , "Slope upwards" , "Get higher" , "Scale or clamber" .)