Tick isn't confused with insect (7)
I believe the answer is:
instant
'tick' is the definition.
(I've seen this before)
'isn't confused with insect' is the wordplay.
'confused' is an anagram indicator.
'with' says to put letters next to each other.
'insect' becomes 'ant' (ant is a kind of insect).
'isnt' with letters rearranged gives 'inst'.
'inst'+'ant'='INSTANT'
(Other definitions for instant that I've seen before include "pressing" , "Not detailed" , "No need to cook" , "The blink of an eye" , "Short time, of the current month" .)