Slow movers ultimately suffer in misusing dope and LSD (8)

'slow movers' is the definition.
(to plod along is to move slowly)

'ultimately suffer in misusing dope and lsd' is the wordplay.
'ultimately' suggests the final letters.
'in' indicates putting letters inside.
'misusing' is an anagram indicator.
'and' means one lot of letters go next to another.
The last letter of 'suffer' is 'r'.
'dope' put after 'lsd' is 'lsddope'.
'lsddope' is an anagram of 'ploddes'.
'r' going into 'ploddes' is 'PLODDERS'.