One child nursed by Nurse Ruby made better (8)
I believe the answer is:
enriched
'made better' is the definition.
(enriching is a kind of making better)
'one child nursed by nurse ruby' is the wordplay.
'one' becomes 'i' (Roman numeral).
'child' becomes 'ch' (abbreviation for child).
'nursed by' means one lot of letters goes inside another.
'nurse' becomes 'EN' (abbreviation for enrolled nurse).
'ruby' becomes 'red' (synonyms).
'i'+'ch'='ich'
'en'+'red'='enred'
'ich' inserted inside 'enred' is 'ENRICHED'.
(Other definitions for enriched that I've seen before include "Improved in quality - made wealthy" , "Made wealthier" .)