Almost entirely foresee GB rower Redgrave’s third son jumping from these? (6,6)

'almost entirely foresee' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'gb rower redgrave's third son jumping from these?' is the wordplay.
I cannot quite understand how this works, but
'gb' could be 'g' (synonyms) and 'g' is located in the answer.
'rower' could be 'oar' (I've seen this in another clue) and 'oar' is found within the answer.
'son' could be 's' (genealogical abbreviation for son) and 's' is found within the answer.
'from' could be 'in' (I've seen this in other clues) and 'in' is found in the answer.
'redgrave's third' could be 'd' (3rd letter of 'redgrave') and 'd' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?