Green character flying a kite around the army centre! (6)
I believe the answer is:
kermit
'green character' is the definition.
The definition suggests a singular noun which matches the answer.
'flying a kite around the army centre' is the wordplay.
'flying' indicates anagramming the letters (letters fly around into new positions).
'around' indicates putting letters inside.
'centre' means to look at the middle letters.
The middle of 'army' is 'rm'.
'kite' with letters rearranged gives 'keit'.
'keit' enclosing 'rm' is 'KERMIT'.
Can you help me to learn more?
(Other definitions for kermit that I've seen before include "Muppet frog" , "Famous TV frog" , "Croaking muppet?" .)