Lover of old, large (and small) illustrations (8)
I believe the answer is:
examples
'illustrations' is the definition.
(I know this)
'lover of old large and small' is the wordplay.
'lover of old' becomes 'ex' (an ex-lover).
'large' becomes 'ample' (similar in meaning).
'and' means one lot of letters go next to another.
'small' becomes 's' (abbreviation - e.g. clothes size).
'ex'+'ample'+'s'='EXAMPLES'
(Other definitions for examples that I've seen before include "Representative samples" , "They illustrate general rules" , "They're characteristic of their kind" , "prototypes" , "Illustrations, instances" .)