Up to middle of week, Dicky is at sea (5-4)
I believe the answer is:
waist-deep
'up to middle' is the definition.
I can't tell whether this defines the answer.
'week dicky is at sea' is the wordplay.
'week' becomes 'w' (abbreviation).
'dicky' is an anagram indicator (dicky can mean ill or non-functioning).
'sea' becomes 'deep' (I can't justify this - if you can you should believe this answer much more).
'is'+'at'='isat'
'isat' anagrammed gives 'aist'.
'w'+'aist'+'deep'='WAIST-DEEP'
'of' is the link.
Can you help me to learn more?
(Other definitions for waist-deep that I've seen before include "(Of water) coming halfway up the body" , "(Of water) covering legs and lower body" .)