One to blend in tea with energy-packed fruit (9)
I believe the answer is:
chameleon
'one to blend in' is the definition.
(I've seen this before)
'tea with energy-packed fruit' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'with' is a charade indicator (letters next to each other).
'energy' becomes 'e' (physics symbol as in E=mce).
'packed' means one lot of letters goes inside another (some letters are packed into others).
'fruit' becomes 'melon' (melon is a kind of fruit).
'e' placed inside 'melon' is 'meleon'.
'cha'+'meleon'='CHAMELEON'
(Other definitions for chameleon that I've seen before include "Variable-colour reptile" , "Colour-changing lizard" , "Self-camouflaging lizard" , "Someone who changes position to suit the situation" , "I'll adapt to fit in" .)