One grazing animals gets air exercising (7)
I believe the answer is:
agister
'one grazing animals' is the definition.
(someone who grazes cattle)
'gets air exercising' is the wordplay.
'exercising' indicates an anagram (letters exercise or move around).
'gets'+'air'='getsair'
'getsair' with letters rearranged gives 'AGISTER'.
(Other definitions for agister that I've seen before include "One grazing cattle for pay; is great (anagram)" , "agricultural officer" , "neat officer" .)