On vacation Susan has trouble with room rate that's poor (6,4)
I believe the answer is:
snails pace
'rate that's poor' is the definition.
(slow pace)
'on vacation susan has trouble with room' is the wordplay.
'on vacation' means to remove the middle letters.
'has' means one lot of letters go next to another.
'trouble' becomes 'ail' (synonyms).
'with' says to put letters next to each other.
'room' becomes 'space' (I've seen this in another clue).
'susan' with its centre taken out is 'sn'.
'sn'+'ail'+'space'='SNAILS PACE'
(Other definitions for snails pace that I've seen before include "Slow rate of progress" , "no rush" , "making slow progress" , "at a very low rate" , "Very slow speed" .)