Old horses produced yearlings Riley dismissed? (4)
I believe the answer is:
nags
'old horses' is the definition.
'nags' can be an answer for 'horses' (nag is a kind of horse). I'm not certain of the 'old' bit.
'produced yearlings riley dismissed?' is the wordplay.
'produced' indicates an anagram.
'dismissed?' indicates named letters should be taken away.
'yearlings' with 'riley' taken away is 'angs'.
'angs' is an anagram of 'NAGS'.
Can you help me to learn more?
(Other definitions for nags that I've seen before include "Scolds - horses" , "Annoys" , "Scolds constantly" , "Constantly reproaches and complains" , "Constantly finds fault" .)