Emma's mother leaves clutching broken elbow, showing guts once (8)

'guts once' is the definition.
(archaic version of 'disembowels')

'emma's mother leaves clutching broken elbow' is the wordplay.
'mother' becomes 'ma' (ma can mean mother).
'leaves' suggests deleting specific letters.
'clutching' means one lot of letters goes inside another.
'broken' is an anagram indicator.
'emmas' with 'ma' removed is 'ems'.
'elbow' is an anagram of 'bowel'.
'ems' placed around 'bowel' is 'EMBOWELS'.

'showing' is the link.