Guard dependent on old queen (6)
I believe the answer is:
warder
'guard dependent on old queen' is the definition.
'warder' can be an answer for 'guard' (I've seen this in another clue). I'm unsure of the 'dependent on old queen' bit.
'guard dependent on old queen' is the wordplay.
I cannot really understand how this works, but
'guard' could be 'ward' (synonyms) and 'ward' is located in the answer.
'queen' could be 'er' (short for Elizabeth Regina ie Queen Elizabeth) and 'er' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for warder that I've seen before include "screw" , "One is in charge of prisoners" , "Gaoler" , "Reward for prison guard" , "keeper" .)