Kids I saw playing around, having a bit of fun (5)
I believe the answer is:
waifs
'kids' is the definition.
(waif is a kind of kid)
'i saw playing around having a bit of fun' is the wordplay.
'playing around' indicates anagramming the letters (I've seen this in other clues).
'having' means one lot of letters goes inside another.
'a bit of' indicates taking the first letters.
The initial letter of 'fun' is 'f'.
'i'+'saw'='isaw'
'isaw' is an anagram of 'wais'.
'wais' placed around 'f' is 'WAIFS'.
(Other definitions for waifs that I've seen before include "Strays" , "Forsaken children" .)