It appears you are looking for CON to make conduct and consign, but contense is not a word. The only three-letter combination you can use in front of TENSE is pretense, which does not work with the other two words. However, if you replace TENSE with DENSE, your question would work.
day
con + sign = consign
con-sign
pro, con
day
day
con consign, conduct, confound, contract ect.....
daydaylightdaybreakdaytime
out
CON
The word is "land." I realize that's not three letters.
front