On reflection, tacks it on to clip (4)
I believe the answer is:
snip
'to clip' is the definition.
('snip' can be a synonym of 'clip')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for snip that I've seen before include "Cut - certainty" , "Cut - price bargain" , "nick)" , "vasectomy?" , "Cut back" .)