Infant dancing across old university water feature (8)
I believe the answer is:
fountain
'water feature' is the definition.
(I've seen this before)
'infant dancing across old university' is the wordplay.
'dancing' indicates anagramming the letters.
'across' is an insertion indicator.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'university' becomes 'u'.
'infant' anagrammed gives 'fntain'.
'o'+'u'='ou'
'fntain' placed around 'ou' is 'FOUNTAIN'.
(Other definitions for fountain that I've seen before include "Ornamental water feature" , "Artificially produced jet of water" , "Give out" , "Man-made water-jet" , "Artificially-produced jet of water" .)