Tablet having no power could create trouble (3)
I believe the answer is:
ill
'trouble' is the definition.
(ill can mean a trouble or problem)
'tablet having no power' is the wordplay.
'tablet' becomes 'pill' (synonyms).
'having no' suggests deleting specific letters.
'power' becomes 'p' (symbol in physics).
'pill' with 'p' removed is 'ILL'.
'could create' is the link.
(Other definitions for ill that I've seen before include "Green round the gills" , "Hardly - sick" , "Unwell, sick" , "Indisposed" , "Where Chicagoans are briefly" .)