Fliers fight and fight with leader of squadron (8)
I believe the answer is:
sparrows
'fliers' is the definition.
(sparrow is a kind of bird)
'fight and fight with leader of squadron' is the wordplay.
'fight' becomes 'spar' (sparring is a kind of fighting).
'and' is a charade indicator (letters next to each other).
'fight' becomes 'row' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'leader of' says to take the initial letters.
The first letter of 'squadron' is 's'.
'spar'+'row'+'s'='SPARROWS'
(Other definitions for sparrows that I've seen before include "These birds warp Ross badly" , "Small brown birds" , "Small singing birds" .)