Force coming from member that is left outside (5)
I believe the answer is:
impel
'force' is the definition.
('impel' can be a synonym of 'force')
'member that is left outside' is the wordplay.
'member' becomes 'mp'.
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'left' becomes 'l' (common abbreviation).
'outside' means one lot of letters goes inside another.
'ie'+'l'='iel'
'mp' inserted into 'iel' is 'IMPEL'.
'coming from' is the link.
(Other definitions for impel that I've seen before include "'Drive, force (5)'" , "Hold together" , "Constrain" , "Goad" , "Urge or drive to do something" .)