A scan screening heart of Moroccan flyer (6)
I believe the answer is:
avocet
'flyer' is the definition.
(type of bird)
'a scan screening heart of moroccan' is the wordplay.
'scan' becomes 'vet' (vet can mean to test or scan).
'screening' means one lot of letters goes inside another (inserted letters are covered or screened by others).
'heart of' means to look at the middle letters.
The middle of 'moroccan' is 'oc'.
'vet' placed around 'oc' is 'vocet'.
'a'+'vocet'='AVOCET'
(Other definitions for avocet that I've seen before include "Shorebird with bill curving upwards" , "Long-legged wading bird with upward-curving bill" , "Shorebird - octave (anag)" , "Curved-bill shore bird" , "Flier" .)