A measure of force to implant monitor in rodent (7)
I believe the answer is:
voltage
'a measure of force' is the definition.
(measure of electromotive force)
'implant monitor in rodent' is the wordplay.
'implant monitor' becomes 'tag' (implant an electronic tag).
'in' indicates putting letters inside.
'rodent' becomes 'vole' (vole is a kind of rodent).
'tag' placed into 'vole' is 'VOLTAGE'.
'to' acts as a link.
(Other definitions for voltage that I've seen before include "current potential" , "Power supply rating" , "Measure of electrical potential" .)