Since you tagged bash:

[[ $string =~ Icecream([^ ]*) ]] && trail=$BASH_REMATCH[1]

More generally, for a search term in $search:

[[ $string =~ $search([^ ]*) ]] && trail=$BASH_REMATCH[1]

Since you tagged bash:

[[ $string =~ (Icecream[^ ]*) ]] && result=${BASH_REMATCH[1]}

More generally, for a search term in $search:

[[ $string =~ ($search[^ ]*) ]] && result=${BASH_REMATCH[1]}

... or with parameter expansion:

# remove any leading text up to -and through- the search text:
x=${string##*$search}

# remove any trailing space onwards
result=$search${x%% *}