Scruffy children — last thing academy needs (5)
I believe the answer is:
seedy
'scruffy' is the definition.
(I know that scruffy can be written as seedy)
'children last thing academy needs' is the wordplay.
I cannot really understand how this works, but
'children' could be 'seed' (I've seen this before) and 'seed' is found in the answer.
A single letter 'y' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for seedy that I've seen before include "under the weather" , "Run-down, squalid" , "Shabby and a bit dubious" , "Not well turned out" , "Unpleasant" .)