Particular footballers with extremely significant debts concealing identity (10)
I believe the answer is:
fastidious
'particular' is the definition.
(similar in meaning)
'footballers with extremely significant debts concealing identity' is the wordplay.
'footballers with' becomes 'fa' (I can't explain this - if you can you should give a lot more credence to this answer).
'extremely' means to remove the middle letters (only the extremes of the word are used).
'debts' becomes 'IOUs' (promises to pay debts).
'concealing' is an insertion indicator.
'identity' becomes 'id' (abbreviation).
'significant' with its centre taken out is 'st'.
'st'+'ious'='stious'
'stious' placed around 'id' is 'stidious'.
'fa'+'stidious'='FASTIDIOUS'
Can you help me to learn more?
(Other definitions for fastidious that I've seen before include "Meticulous" , "Attentive to detail" .)