Noticing headless insect in grass (6)
I believe the answer is:
seeing
'noticing' is the definition.
(I've seen this before)
'headless insect in grass' is the wordplay.
'headless' means to remove the first letter.
'insect' becomes 'bee' (bee is a kind of insect).
'in' indicates putting letters inside.
'grass' becomes 'sing' (I've seen this in other clues**).
'bee' with its initial letter taken off is 'ee'.
'ee' placed within 'sing' is 'SEEING'.
(Other definitions for seeing that I've seen before include ". . . . . . is believing, they say" , "Meeting" , "since" , "Observing - understanding" , "Perceiving by eye" .)