Plane tree whose leaves conceal the cuckoo and rook (7)
I believe the answer is:
fighter
'plane' is the definition.
(I know that fighter is a type of plane)
'conceal the cuckoo and rook' is the wordplay.
'conceal' becomes 'fig' (I can't explain this - if you can you should believe this answer much more).
'cuckoo' indicates an anagram.
'and' means one lot of letters go next to another.
'rook' becomes 'R' (chess abbreviation).
'the' with letters rearranged gives 'hte'.
'fig'+'hte'+'r'='FIGHTER'
'tree whose leaves' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for fighter that I've seen before include "Freight (anag.)" , "Fast military aircraft" , "Warplane" , "Professional boxer - a person with determination" , "Combatant, battler" .)