Greek character stays erect when aroused, and that's not all (2,6)
I believe the answer is:
et cetera
'that's not all' is the definition.
I can't judge whether this defines the answer.
'greek character stays erect when aroused' is the wordplay.
'greek character' becomes 'eta' (letter from the Greek alphabet).
'stays' is an insertion indicator (\'stay\' could historically mean restrain or curb).
'when aroused' indicates an anagram (I've seen this in other clues).
'erect' with letters rearranged gives 'ceter'.
'eta' enclosing 'ceter' is 'ET CETERA'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for et cetera that I've seen before include "something similar" , "And the rest (Latin)" , "'And so forth (2,6)'" , "Drive out, expel" , "That can reduce length of sentence" .)