Rob's cop somehow is on the nose (9)
I believe the answer is:
proboscis
'the nose' is the definition.
(proboscis is a kind of nose)
'rob's cop somehow is' is the wordplay.
'somehow' indicates an anagram.
'robs'+'cop'='robscop'
'robscop' with letters rearranged gives 'probosc'.
'probosc'+'is'='PROBOSCIS'
'on' acts as a link.
(Other definitions for proboscis that I've seen before include "Snout" , "MONKEY" , "Elephant's trunk" , "The human nose" , "Elephantine nose" .)