Exposes tips holding needle (9)
I believe the answer is:
endangers
'exposes' is the definition.
('endanger' can be a synonym of 'expose')
'tips holding needle' is the wordplay.
'tips' becomes 'ends'.
'holding' is an insertion indicator.
'needle' becomes 'anger'.
'ends' placed around 'anger' is 'ENDANGERS'.
(Other definitions for endangers that I've seen before include "Puts into jeopardy" , "poses a threat" , "Imperils" , "Risks" , "Puts in peril" .)