Animated green flying alien I see (9)
I believe the answer is:
energetic
'animated' is the definition.
(thesaurus)
'green flying alien i see' is the wordplay.
'flying' indicates an anagram (letters fly around into new positions).
'alien' becomes 'et' (extraterrestrial).
'see' becomes 'C' (the word for the letter, according to Chambers).
'green' anagrammed gives 'energ'.
'energ'+'et'+'i'+'c'='ENERGETIC'
(Other definitions for energetic that I've seen before include "Lively, spirited" , "Forceful and with great vitality" , "Vigorous and dynamic" , "Lively, dynamic" , "High-powered" .)