On board, a way into starting exploration for fish (8)
I believe the answer is:
sardines
'for fish' is the definition.
(I've seen this before)
'on board a way into' is the wordplay.
'on board' becomes 'sines' (I am not sure about this - if you are sure you should believe this answer much more).
'way' becomes 'rd' (short for road).
'into' is an insertion indicator.
'a'+'rd'='ard'
'sines' going around 'ard' is 'SARDINES'.
'starting exploration' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sardines that I've seen before include "Small fish, usually canned" , "Cumulative hiding game" , "Children's game - fish" , "Young pilchards" , "Aridness of small fish" .)