Laid up in Caribbean island? It’s the passion fruit! (10)
I believe the answer is:
'the passion fruit' is the definition.
(name for various species of passion-flower)
'laid up in caribbean island?' is the wordplay.
'laid up' becomes 'ill' ('ill' can be similar in meaning to 'laid up').
'in' is an insertion indicator.
'caribbean island?' becomes 'grenada' (I've seen this before).
'ill' placed inside 'grenada' is 'GRENADILLA'.
'it's' is the link.
(Another definition for grenadilla that I've seen is " fruit".)