Initially looked in toilet for online journal (4)
I believe the answer is:
blog
'online journal' is the definition.
(I've seen this before)
'initially looked in toilet' is the wordplay.
'initially' suggests taking the first letters.
'in' is an insertion indicator.
'toilet' becomes 'bog' (informal term for toilet).
The initial letter of 'looked' is 'l'.
'l' inserted within 'bog' is 'BLOG'.
'for' is the link.
(Other definitions for blog that I've seen before include "Online journal" , "published journal" , "Personal opinion website" , "Internet journal" , "Web diary" .)