Insect that is loud by meadow (4)
I believe the answer is:
flea
'insect' is the definition.
(flea is a kind of insect)
'loud by meadow' is the wordplay.
'loud' becomes 'f' (A musical term).
'by' says to put letters next to each other.
'meadow' becomes 'lea' (I've seen this before**).
'f'+'lea'='FLEA'
'that is' acts as a link.
(Other definitions for flea that I've seen before include "Small parasitic insect" , "Leaping insect" , "Jumping bloodsucker" , "Tiny parasite" , "Member of a circus?" .)