Get into exercises with clear speed (9)
I believe the answer is:
penetrate
'get into' is the definition.
(penetrating is a kind of getting into)
'exercises with clear speed' is the wordplay.
'exercises' becomes 'pe'.
'with' means one lot of letters go next to another.
'clear' becomes 'net' (as in net profit).
'speed' becomes 'rate' (rate is a kind of speed**).
'pe'+'net'+'rate'='PENETRATE'
(Other definitions for penetrate that I've seen before include "probe" , "Go through" , "Force way through, into" , "Pass into or through" , "Run through" .)