Old coat of rags concealing ample bust for models (9)

'for models' is the definition.
('exemplar' can be a synonym of 'model')

'old coat of rags concealing ample bust' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'coat of' means to remove the middle letters (only the letters that coat the word).
'concealing' indicates putting letters inside.
'bust' indicates an anagram.
'rags' with its middle taken out is 'rs'.
'ex'+'rs'='exrs'
'ample' is an anagram of 'empla'.
'exrs' going around 'empla' is 'EXEMPLARS'.