With a string like that in A2, select B2 and do Insert > Name >Define

ToTime Refers to: =EVALUATE(SUBSTITUTE(SUBSTITUTE(SUBSTITUTE(A2, "H ", "/24 + "),"M ", "/1440 + "), "S", "/86400"))

Then in B2 and copy down, =ToTime

      -----A----- ---B----
  1      Input     Output 
  2   55M 25S     00:55:25
  3   01H 32S     01:00:32
  4   01H 01M 15S 01:01:15
  5   01H 03M 11S 01:03:11
  6   01H 04M 32S 01:04:32