These patches of ground aid fliers (9)
I believe the answer is:
airfields
'these patches' is the definition.
The definition suggests an adverb but the answer is not.
'ground aid fliers' is the wordplay.
'ground' indicates anagramming the letters (grind the letters ).
'aid'+'fliers'='aidfliers'
'aidfliers' anagrammed gives 'AIRFIELDS'.
'of' is the link.
(Other definitions for airfields that I've seen before include "places to land" , "Flying bases" , "Where strips are" .)