An illustration of former lover being liberal (7)
I believe the answer is:
example
'an illustration' is the definition.
(I know that illustration can be written as example)
'former lover being liberal' is the wordplay.
'former lover' becomes 'ex' (ex-lover).
'being liberal' becomes 'ample' (I've seen this before).
'ex'+'ample'='EXAMPLE'
'of' is the link.
(Other definitions for example that I've seen before include "Paradigm or model" , "Specimen, illustration" , "Illustration or paradigm" , "Standard" , "Case in point" .)