Her day on guard is weird -- crude but effective (5-3-5)
I believe the answer is:
rough-and-ready
'crude but effective' is the definition.
(I've seen this before)
'her day on guard is weird' is the wordplay.
'is weird' is an anagram indicator.
'her'+'day'+'on'+'guard'='herdayonguard'
'herdayonguard' with letters rearranged gives 'ROUGH-AND-READY'.
(Other definitions for rough-and-ready that I've seen before include "Serving well enough for the task" , "Crude but effective" , "Lacking refinement but serving a purpose" , "Crude - unpolished" , "Easily improvised" .)