Number having an inclination for restraint (5)
I believe the answer is:
cramp
'restraint' is the definition.
(I've seen this before)
'number having an inclination' is the wordplay.
'number' becomes 'c' (C is an example).
'having' is a charade indicator (letters next to each other).
'an inclination' becomes 'ramp'.
'c'+'ramp'='CRAMP'
'for' acts as a link.
(Other definitions for cramp that I've seen before include "common among writers" , "Contract" , "Form of muscular pain" , "Painful muscle problem" , "Confine - muscular spasm" .)