Compensation when a horse gets long in the tooth (7)
I believe the answer is:
damages
'compensation' is the definition.
(damages is a kind of compensation)
'a horse gets long in the tooth' is the wordplay.
'a horse' becomes 'dam' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'gets long in the tooth' becomes 'ages' (I've seen this in another clue).
'dam'+'ages'='DAMAGES'
'when' is the link.
Can you help me to learn more?
(Other definitions for damages that I've seen before include "Money awarded as compensation" , "weakens" , "Harms" , "Moneys paid as compensation for an injury" , "Hurts" .)