Small, tricky splinter (5)
I believe the answer is:
shard
'splinter' is the definition.
(thesaurus)
'small tricky' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'tricky' becomes 'hard' (similar in meaning).
's'+'hard'='SHARD'
(Other definitions for shard that I've seen before
include
"Broken fragment"
,
"Go well with; attire"
,
"Broken piece of a brittle artefact"
,
"Bit of glass"
,
"Shell