Frequently have nothing to measure (3)
I believe the answer is:
oft
'frequently' is the definition.
(oft can mean frequently, eg oft-quoted)
'nothing to measure' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'to measure' becomes 'ft' (ft is a kind of measure).
'o'+'ft'='OFT'
'have' is the link.
(Other definitions for oft that I've seen before include "Quite frequently, according to the poet" , "Many times, to the poet" , "Consistently" , "''... in the stilly night'' (Moore melody)" , "Many times (archaic)" .)