Speed on, shot in the foot (7)
I believe the answer is:
spondee
'the foot' is the definition.
(type of metrical foot in poetry)
'speed on shot' is the wordplay.
'shot' indicates an anagram.
'speed'+'on'='speedon'
'speedon' with letters rearranged gives 'SPONDEE'.
'in' is the link.
(Other definitions for spondee that I've seen before include "No speed required for poetic metrical foot" , "Metric foot of two long syllables" , "bit of verse" .)